Electric storage battery construction and method of manufacture

ABSTRACT

A battery includes a feedthrough pin which is electrically connected to an inner end of an electrode substrate. A mandrel on the pin can permit the pin/mandrel to be used as an arbor to facilitate winding layers of a spiral jellyroll electrode assembly. The pin can serve as one of the battery terminals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.10/167,688, filed Jun. 12, 2002, issued as U.S. Pat. No. 6,670,071 onDec. 30, 2003, which claims the benefit of U.S. Provisional ApplicationNo. 60/348,655, filed Jan. 15, 2002, each of which is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates generally to electric storage batteries and moreparticularly to a battery construction, and method of manufacturethereof, suitable for use in implantable medical devices.

BACKGROUND OF THE INVENTION

Rechargeable electric storage batteries are commercially available in awide range of sizes for use in a variety of applications. As batterytechnology continues to improve, batteries find new applications whichimpose increasingly stringent specifications relating to physical sizeand performance. Thus, new technologies have yielded smaller and lighterweight batteries having longer storage lives and higher energy outputcapabilities enabling them to be used in an increasing range ofapplications, including medical applications, where, for example, thebattery can be used in a medical device which is implanted in apatient's body. Such medical devices can be used to monitor and/or treatvarious medical conditions.

Batteries for implantable medical devices are subject to very demandingrequirements, including long useful life, high power output, lowself-discharge rates, compact size, high reliability over a long timeperiod, compatibility with the patient's internal body chemistry, etc.Although various battery chemistries have been tried, lithium iontechnology is generally accepted as the preferred chemistry for medicalimplant applications.

Such electric storage batteries are generally comprised of a tubularmetal case enveloping an interior cavity which contains an electrodeassembly surrounded by a suitable electrolyte. The electrode assemblygenerally comprises a plurality of positive electrode, negativeelectrode, and separator layers which are typically stacked and/orspirally wound to form a jellyroll. The positive electrode is generallyformed of a metal substrate having positive active material coated onboth faces of the substrate. Similarly, the negative electrode is formedof a metal substrate having negative active material coated on bothfaces of the substrate. In forming an electrode assembly, separatorlayers are interleaved between the positive and negative electrodelayers to provide electrical isolation.

SUMMARY OF THE INVENTION

The present invention is directed to an electric storage batteryincorporating one or more aspects described herein for enhancing batteryreliability while minimizing battery size. In addition, the invention isdirected to a method for efficiently manufacturing the battery at arelatively low cost.

In accordance with a first significant aspect of the invention, afeedthrough pin is provided which is directly physically andelectrically connected to the inner end of an electrode substrate (e.g.,positive), as by welding. The pin is used during the manufacturingprocess as an arbor to facilitate winding the layers to form anelectrode assembly jellyroll. Additionally, in the fully manufacturedbattery, the pin extends through a battery case endcap and functions asone of the battery terminals. The battery case itself generallyfunctions as the other battery terminal.

More particularly, in accordance with an exemplary preferred embodiment,the inner end of the positive electrode substrate is spot welded to thefeedthrough pin to form an electrical connection. The substrate, e.g.,aluminum, can be very thin, e.g., 0.02 mm, making it difficult to form astrong mechanical connection to the pin, which is preferably constructedof a low electrical resistance, highly corrosion resistant material,e.g., platinum iridium, and can have a diameter on the order of 0.40 mm.In order to mechanically reinforce the pin and secure the pin/substrateconnection, a slotted C-shaped mandrel is provided. The mandrel isformed of electrically conductive material, e.g., titanium-6Al-4V, andis fitted around the pin, overlaying the pin/substrate connection. Themandrel is then preferably welded to both the pin and substrate. Themandrel slot defines a keyway for accommodating a drive key which can bedriven to rotate the mandrel and pin to wind the electrode assemblylayers to form the spiral jellyroll.

In accordance with a further significant aspect of the invention, theouter layer of the jellyroll is particularly configured to minimize thesize, i.e., outer radius dimension, of the jellyroll. More particularly,in the exemplary preferred embodiment, the active material is removedfrom both faces of the negative electrode substrate adjacent its outerend. The thickness of each active material coat can be about 0.04 mm andthe thickness of the negative substrate can be about 0.005 mm. By baringthe outer end of the negative electrode substrate, it can be adhereddirectly, e.g., by an appropriate adhesive tape, to the next inner layerto close the jellyroll to while minimizing the roll outer radiusdimension.

A battery case in accordance with the invention is comprised of atubular case body having open first and second ends. The feedthrough pinpreferably carries a first endcap physically secured to, butelectrically insulated from, the pin. This first endcap is preferablysecured to the case body, as by laser welding, to close the open firstend and form a leak free seal. With the jellyroll mounted in the caseand the first endcap sealed, the interior cavity can thereafter befilled with electrolyte from the open second end.

In accordance with a still further aspect of the invention, thejellyroll assembly is formed with a flexible electrically conductive tabextending from the negative electrode substrate for electricalconnection to the battery case. In accordance with a preferredembodiment, the tab is welded to a second endcap which is in turn weldedto the case. The tab is sufficiently flexible to enable the secondendcap to close the case body second end after the interior cavity isfilled with electrolyte via the open second end. In accordance with anexemplary preferred embodiment, the tab is welded to the inner face ofthe second endcap such that when the jellyroll is placed in the body,the tab locates the second endcap proximate to the body withoutobstructing the open second end. After electrolyte filling, the casebody is sealed by bending the tab to position the second endcap acrossthe body second end and then laser welding the endcap to the case body.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side view of a feedthrough pin subassembly in accordancewith the invention;

FIG. 2 is a longitudinal sectional view through the subassembly of FIG.1;

FIG. 3 is a plan view of a positive electrode strip utilized in theexemplary preferred electrode assembly in accordance with the invention;

FIG. 4 is a side view of the positive electrode strip of FIG. 3;

FIG. 5 is an enlarged sectional view of the area A of FIG. 4 showing theinner end of the positive electrode strip of FIGS. 3 and 4;

FIG. 6 is an isometric view showing the bared inner end of the positiveelectrode substrate spot welded to the feedthrough pin and configured toreceive a C-shaped mandrel thereon;

FIG. 7 is an end view showing the C-shaped mandrel being crimped to thepin and electrode;

FIG. 8 is an end view showing the C-shaped mandrel mounted on the pinand capturing the positive electrode substrate therebetween;

FIG. 9 is an isometric view depicting a drive key accommodated in theslot of the C-shaped mandrel;

FIG. 10 is a plan view showing the drive key coupled to a drive motorfor rotating the C-shaped mandrel;

FIG. 11 is a schematic end view depicting how rotation of the C-shapedmandrel and pin can wind positive electrode, negative electrode, andseparator strips to form a spiral jellyroll electrode assembly;

FIG. 12 is a plan view of a negative electrode strip utilized in theexemplary preferred electrode assembly in accordance with the invention;

FIG. 13 is a side view of the negative electrode strip of FIG. 12;

FIG. 14 is an enlarged sectional view of the area A of FIG. 13 showingthe inner end of the negative electrode strip of FIGS. 12 and 13;

FIG. 15 is an enlarged sectional view of the area B of FIG. 13 showingthe outer end of the negative electrode strip of FIGS. 11 and 12;

FIGS. 16A and 16B are isometric and cross sectional views, respectively,showing the layers of a spirally wound electrode assembly, i.e.,jellyroll;

FIG. 17 is a plan view of the negative electrode strip showing theattachment of a flexible electrically conductive tab to the bared outerend of the negative electrode substrate;

FIG. 18 is an enlarged sectional view showing how the outer turn of thenegative electrode strip is taped to the next inner layer to close thejellyroll to minimize its outer radius dimension;

FIG. 19 is an isometric view depicting the jellyroll electrode assemblybeing inserted into a cylindrical battery case body;

FIG. 20 is an isometric view showing a battery case body with thenegative electrode tab extending from the open case body;

FIG. 21 is an isometric view showing how the negative electrode tab ismechanically and electrically connected to an endcap for sealing thecase body second end;

FIG. 22 is a side view showing how the negative electrode tab holds thesecond endcap proximate to the case body second end without obstructingthe open second end;

FIG. 23 is a front view showing the weld position and the relationshipbetween the various components; and

FIG. 24 is an enlarged sectional view of the second end of the batterycase showing the endcap in sealed position.

DETAILED DESCRIPTION

Attention is initially directed to FIGS. 1 and 2 which illustrate apreferred feedthrough pin subassembly 10 utilized in accordance with thepresent invention. The subassembly 10 is comprised of an elongate pin12, preferably formed of a solid electrically conductive material,having low electrical resistance and high corrosion resistance such asplatinum iridium, preferably 90Pt/10Ir. The pin 12 extends through, andis hermetically sealed to a header 14. The header 14 is comprised ofdielectric disks, e.g., ceramic, 16 and 18 which sandwich a glass hollowcylinder 20 therebetween. The glass hollow cylinder is hermeticallysealed to the pin 12. The outer surface of the glass hollow cylinder 20is sealed to the inner surface of an electrically conductive hollowmember 22, e.g., titanium-6Al-4V. As will be seen hereinafter, theconductive hollow material 22 functions as a battery case endcap in thefinal product to be described hereinafter.

Attention is now directed to FIGS. 3, 4, and 5 which illustrate apreferred positive electrode strip 30 which is utilized in thefabrication of a preferred spirally wound jellyroll electrode assemblyin accordance with the present invention. The positive electrode strip30 is comprised of a metal substrate 32 formed, for example, ofaluminum. Positive electrode active material 34, 36 is deposited,respectively on the upper and lower faces 38 and 40 of the substrate 32.Note in FIGS. 3, 4, and 5 that the right end of the substrate 32 isbare, i.e. devoid of positive active material on both the upper andlower faces 38, 40.

It is to be pointed out that exemplary dimensions are depicted in FIGS.1-5 and other figures herein. These exemplary dimensions are providedprimarily to convey an order of magnitude to the reader to facilitate anunderstanding of the text and drawings. Although the indicateddimensions accurately reflect one exemplary embodiment of the invention,it should be appreciated that the invention can be practiced utilizingcomponents having significantly different dimensions.

FIG. 6 depicts an early process step for manufacturing a battery inaccordance with the invention utilizing the pin subassembly 10 (FIGS. 1,2) and the positive electrode strip 30 (FIGS. 3-5). A topside electrodeinsulator (not shown), which may comprise a thin disk of DuPont Kapton®polyimide film, is slipped onto the pin 12 adjacent the header 14. Inaccordance with the present invention, the bare end of the electrodestrip substrate 32 is electrically connected to the pin 12 preferably byresistance spot welding, shown at 44. Alternatively, substrate 32 may beultrasonically welded to the pin 12. The thinness, e.g. point 0.02 mm ofthe substrate 32, makes it very difficult to form a strong mechanicalconnection between the substrate and the pin 12. Accordingly, inaccordance with a significant aspect of the present invention, anelongate C-shaped mandrel 48 is provided to mechanically reinforce thepin 12 and secure the substrate 32 thereto.

The mandrel 48 preferably comprises an elongate titanium or titaniumalloy such as Ti-6Al-4V tube 50 having a longitudinal slot 52 extendingalong the length thereof. The arrow 54 in FIG. 6 depicts how the mandrel48 is slid over the pin 12 and substrate 32, preferably overlaying theline of spot welds 44. The mandrel 48, pin 12, and substrate 32 are thenpreferably welded together, such as by resistance spot welding or byultrasonic welding. Alternatively, the mandrel 48 may be crimped ontothe pin 12 at least partially closing the “C” to create a strongmechanical connection. In the case of forming only a mechanicalconnection and not necessarily a gas-tight electrical connection betweenthe mandrel 48 and the pin and substrate, the mandrel material ispreferably made of a material that will not lead to electrolysis. Whenused with electrolytes that tend to contain hydrofluoric acid, themandrel is preferably made of 304, 314, or 316 stainless steels oraluminum or an alloy thereof chosen for its compatibility with the othermaterials. FIG. 7 is an end view showing the step of crimping themandrel 48 to the pin 12 and substrate 32. Supporting die 126 is used tosupport the mandrel 48 and crimping dies 124 and 125 are used to deformthe edges of the mandrel 48 to bring them closer together andmechanically connect the mandrel 48 to the pin 12 and substrate 32. Bycrimping in the direction of arrows 127 and 128, a strong connection isformed without damaging the thin electrode or disturbing the electricalconnection between the pin and the electrode.

FIG. 8 is an end view showing the slotted mandrel 48 on the pin 12 withthe substrate 32 extending tangentially to the pin 12 and terminatingadjacent the interior surface of the mandrel tube 50. The tube 50 ispreferably sufficiently long so as to extend beyond the free end of thepin 12. As depicted in FIG. 9, this enables a drive key 56 to extendinto the mandrel slot 52.

FIG. 10 schematically depicts a drive motor 60 for driving the drive key56 extending into mandrel slot 52. With the pin subassembly header 14supported for rotation (not shown), energization of the motor 60 willorbit the key drive 56 to rotate the mandrel 48 and subassembly 10around their common longitudinal axes. The rotation of the mandrel 48and subassembly 10 is employed to form a jellyroll electrode assembly inaccordance with the present invention.

More particularly, FIG. 11 depicts how a jellyroll electrode assembly isformed in accordance with the present invention. The bare end of thesubstrate 32 of the positive electrode strip 30 is electricallyconnected to the pin 12 as previously described. The conductive mandrel48 contains the pin 12 and bare substrate end, being welded to both aspreviously described. A strip of insulating separator material 64extending from opposite directions is introduced between the mandrel 48and positive electrode substrate 32, as shown. A negative electrodestrip 70 is then introduced between the portions of the separatormaterial extending outwardly from mandrel 48.

The preferred exemplary negative electrode strip 70 is depicted in FIGS.12-15. The negative electrode strip 70 is comprised of a substrate 72,e.g. titanium, having negative active material formed on respectivefaces of the substrate. More particularly, note in FIG. 14 that negativeactive material 74 is deposited on the substrate upper surface 76 andnegative active material 78 is deposited on the substrate lower surface80. FIG. 14 depicts the preferred configuration of the inner end 82 ofthe negative electrode strip 70 shown at the left of FIGS. 12 and 13.FIG. 15 depicts the configuration of the outer end 83 of the negativeelectrode strip 70 shown at the right side of FIGS. 12 and 13.

Note in FIG. 14 that one face of the substrate inner end 82 is bared.This configuration can also be noted in FIG. 11 which shows how thenegative substrate inner end 82 is inserted between turns of theseparator strip 64. After the strip 70 has been inserted as depicted inFIG. 11, the aforementioned drive motor 60 is energized to rotate pin 12and mandrel 48, via drive key 56, in a counterclockwise direction, asviewed in FIG. 11. Rotation of pin 12 and mandrel 48 functions to windpositive electrode strip 30, separator strip 64, and negative electrodestrip 70, into the spiral jellyroll assembly 84, depicted in FIG. 16A.The assembly 84 comprises multiple layers of strip material so that across section through the assembly 84 reveals a sequence of layers inthe form pos/sep/neg/sep/pos/sep/neg/ . . . , etc., as shown in FIG.16B.

FIG. 15 depicts a preferred configuration of the outer end 83 of thenegative electrode strip 70. Note that the outer end 88 of the substrate72 is bared on both its top and bottom faces. Additionally, as shown inFIG. 17, a flexible metal tab 90 is welded crosswise to the substrate 72so as to extend beyond edge 92. More particularly, note that portion 94of tab 90 is cantilevered beyond edge 92 of negative electrode strip 70.This tab portion, as will be described hereinafter, is utilized tomechanically and electrically connect to an endcap for closing a batterycase.

Attention is now called to FIG. 18, which illustrates a preferredtechnique for closing the jellyroll assembly 84. That is, the bared end88 of the negative electrode substrate 72 extending beyond the negativeactive material coat 78 is draped over the next inner layer of thejellyroll assembly 84. The end 88 can then be secured to the next innerlayer, e.g., by appropriate adhesive tape 96. One such suitable adhesivetape is DuPont Kapton® polyimide tape. It is important to note that theouter end configuration 88 of the negative electrode strip 70 enablesthe outer radius dimension of the jellyroll assembly 84 to be minimizedas shown in FIG. 18. More particularly, by baring the substrate 72beyond the active material 78, the tape 96 is able to secure thesubstrate end without adding any radial dimension to the jellyrollassembly. In other words, if the outer end of the substrate were notsufficiently bared, then the tape 96 would need to extend over theactive material and thus add to the outer radius dimension of thejellyroll 84. Furthermore, the bare substrate 72 is more flexible thanthe substrate coated with active material 78 and conforms more readilyto the jellyroll assembly 84, making it easier to adhere it to thesurface of the jellyroll. These space savings, although seemingly small,can be clinically important in certain medical applications. It shouldbe noted that the electrode need only be bared at an end portion longenough to accommodate the tape 96, as shown in FIG. 18. Because theuncoated substrate does not function as an electrode, it would wastespace in the battery to bare any more than necessary to accommodate thetape. In a preferred embodiment, the length of uncoated substrate isbetween 1 and 8 mm, and more preferably about 2 mm.

FIG. 19 depicts the completed jellyroll assembly 84 and shows thecantilevered tab portion 94 prior to insertion into a battery case body100. The case body 100 is depicted as comprising a cylindrical metaltube 101 having an open first end 104 and open second end 106. Arrow 107represents how the jellyroll assembly 84 is inserted into thecylindrical tube 101. FIG. 20 depicts the jellyroll assembly 84 withinthe tube 101 with the cantilevered negative electrode tab 94 extendingfrom the case open second end 106. The case open first end 104 is closedby the aforementioned header 14 of the pin subassembly 10 shown in FIGS.1 and 2. More particularly, note that the metal hollow member 22 isconfigured to define a reduced diameter portion 108 and shoulder 110.The reduced diameter portion 108 is dimensioned to fit into the open end104 of the cylindrical tube 101 essentially contiguous with the tube'sinner wall surface. The shoulder 110 of the hollow member 22 engages theend of the case tube 101. This enables the surfaces of the reduceddiameter portion 108 and shoulder 110 to be laser welded to the end ofthe case 100 to achieve a hermetic seal.

Attention is now directed to FIGS. 21-24, which depict the tab 94extending from the second open end 106 of the case tube 101. Note thatthe tab 94 extends longitudinally from the body close to the case tubeadjacent to tube's inner wall surface. In accordance with a preferredembodiment of the invention, the tab 94 is welded at 110 to the innerface 112 of a circular second endcap 114. In accordance with a preferredembodiment, the tab 94 is sufficiently long to locate the weld 110beyond the center point of the circular endcap 114. More particularly,note in FIGS. 21-24 that by locating the weld 110 displaced from thecenter of the cap 114, the tab 94 can conveniently support the endcap114 in a vertical orientation as depicted in FIG. 22 misaligned withrespect to the open end 106. This end cap position approximatelyperpendicular to the end 122 of the case 100 is a first bias positionwherein the end cap advantageously tends to remain in that orientationwith the case end open prior to filling. To further describe therelationship between the weld location and the various components, FIG.23 shows a front view with various dimensions. L represents the lengthfrom the weld 110 to the top of the case 100 as measured parallel to theedge of the case. R is the radius of the end cap 114. For the preferredgeometry, L≦2R. Weld 110 is preferably made above the center point 111of the end cap 114. Preferably, the end cap 114 overlaps the case 100 byapproximately R/2. By configuring the tab 94 and weld 110 as indicated,the endcap 114 can be supported so that it does not obstruct the openend 106, thereby facilitating electrolyte filling of the case interiorcavity via open end 106. A filling needle or nozzle can be placedthrough open end 106 to fill the case. This obviates the need for aseparate electrolyte fill port, thereby reducing the number ofcomponents and number of seals to be made, thus reducing cost andimproving reliability. Furthermore, for small medical batteries, the endcaps would be very small to have fill ports therein. In a preferredembodiment in which the case wall is very thin, for example, 0.002inches, providing a fill port in the side wall of the case would beimpractical. Even in the case of larger devices where space is lesscritical and the wall is more substantial, providing a fill port in theside of the case would mean the electrolyte would have a very long pathlength to wet the jellyroll. Note that while the case could be filledwith electrolyte prior to welding tab 94 to endcap 114, it would bedifficult and messy to do so. Therefore, it is advantageous to configurethe tab 94 and weld 110 as described to allow the weld to be made priorto filling.

Preferably before filling, a bottomside electrode insulator (not shown),which may comprise a thin disk of DuPont Kapton® polyimide film, isinstalled into the case between the rolled electrode assembly and thestill open end of the battery case.

In a preferred filing method, there is a channel of air between the pinand the crimped or welded C-shaped mandrel, which is used as a conduitfor quickly delivering the electrolyte to the far end of the battery andto the inside edges of the electrodes within the jellyroll. Filling fromthe far end of the battery prevents pockets of air from being trapped,which could form a barrier to further filling. This facilitates andspeeds the filling process, ensuring that electrolyte wets the entirebattery.

Thereafter, the flexible tab 94 can be bent to the configurationdepicted in FIG. 24. Note that the endcap 114 is configured similarly toheader hollow member 22 and includes a reduced diameter portion 118 anda shoulder 120. The reduced diameter portion snugly fits against theinner surface of the wall of tube 101 with the endcap shoulder 120bearing against the end 122 of the cylindrical case 100. The relativelylong length of the tab 94 extending beyond the center point of theendcap surface 112 minimizes any axial force which might be exerted bythe tab portion 94 tending to longitudinally displace the endcap 114.The end cap position covering the end 122 of the case 100 is a secondbias position wherein the end cap advantageously tends to remain in thatorientation prior to welding. With the endcap in place, it can then bereadily welded to the case wall 101 to hermetically seal the battery.With tab 90 welded to negative substrate 72 and with the negativeelectrode strip 70 as the outermost layer of the jellyroll, the endcap114 becomes negative. In turn, welding the endcap 114 to the case 100renders the case negative.

From the foregoing, it should now be appreciated that an electricstorage battery construction and method of manufacture have beendescribed herein particularly suited for manufacturing very small,highly reliable batteries suitable for use in implantable medicaldevices. Although a particular preferred embodiment has been describedherein and exemplary dimensions have been mentioned, it should beunderstood that many variations and modifications may occur to thoseskilled in the art falling within the spirit of the invention and theintended scope of the appended claims.

1. An electrode assembly, comprising: an electrically conductive,elongate pin; an elongate mandrel mounted on at least a portion of thepin, the mandrel including a longitudinal slot; a first electrode stripin electrical communication with the pin and a second electrode stripelectrically insulated from the pin, the first electrode strip and thesecond electrode strip being wound around the pin; and the firstelectrode strip extending through the mandrel slot.
 2. The electrodeassembly of claim 1, wherein a portion of the pin extends beyond thespiral roll to form a battery terminal.
 3. The electrode assembly ofclaim 1, wherein the mandrel is crimped onto the pin.
 4. The electrodeassembly of claim 1, wherein the mounted mandrel has a channel throughwhich electrolyte can be injected.
 5. The electrode assembly of claim 1,wherein at least one separator strip separates the first electrode stripand the second electrode strip.
 6. The electrode assembly of claim 1,wherein a portion of the first electrode strip is positioned between themandrel and the pin.
 7. The electrode assembly of claim 1, wherein thefirst electrode strip includes active material positioned on asubstrate, the substrate being positioned between the mandrel and thepin without the active material being positioned between the mandrel andthe pin.
 8. The electrode assembly of claim 1, wherein at least one welddirectly connects the first electrode strip to the pin.
 9. The electrodeassembly of claim 1, wherein the pin includes an alloy of PtIr alloy.10. The electrode assembly of claim 1, further comprising: a first endcap mounted on the pin, the first end cap including an electricalinsulator, the pin extending through the electrical insulator, and thepin being hermetically sealed to the electrical insulator.
 11. Theelectrode assembly of claim 1, wherein a weld attaches the mandrel tothe pin.
 12. The electrode assembly of claim 1, wherein the mandrelincludes titanium or an alloy of titanium.
 13. The electrode assembly ofclaim 1, wherein the mandrel includes a tube.
 14. The electrode assemblyof claim 13, wherein the pin is positioned in an interior of the tube.15. The electrode assembly of claim 1, wherein the mandrel has ac-shaped cross-section.
 16. The electrode assembly of claim 1, whereinthe mandrel is fitted around the pin such that the first electrode stripand the second electrode strip are wound around the pin and the mandrel.17. The electrode assembly of claim 1, wherein the mandrel is areinforcing mandrel.
 18. An electrode assembly, comprising: anelectrically conductive, elongate pin; an elongate mandrel mounted on atleast a portion of the pin; a first electrode strip in electricalcommunication with the pin and a second electrode strip electricallyinsulated from the pin, the first electrode strip and the secondelectrode strip being wound around the pin, and a portion of the firstelectrode strip is positioned between the mandrel and the pin; and afirst end cap mounted on the pin; the first end cap including anelectrical insulator, the pin extending through the electricalinsulator, and the pin being hermetically sealed to the electricalinsulator.
 19. The electrode assembly of claim 18, wherein a portion ofthe pin extends beyond the spiral roll to form a battery terminal. 20.The electrode assembly of claim 18, wherein the mandrel is crimped ontothe pin.
 21. The electrode assembly of claim 18, wherein the mountedmandrel has a channel through which electrolyte can be injected.
 22. Theelectrode assembly of claim 18, wherein at least one separator stripseparates the first electrode strip and the second electrode strip. 23.The electrode assembly of claim 18, wherein the first electrode stripincludes active material positioned on a substrate, the substrate beingpositioned between the mandrel and the pin without the active materialbeing positioned between the mandrel and the pin.
 24. The electrodeassembly of claim 18, wherein at least one weld directly connects thefirst electrode strip to the pin.
 25. The electrode assembly of claim18, wherein the pin includes an alloy of PtIr alloy.
 26. The electrodeassembly of claim 18, wherein a weld attaches the mandrel to the pin.27. The electrode assembly of claim 18, wherein the mandrel includestitanium or an alloy of titanium.
 28. The electrode assembly of claim18, wherein the mandrel includes a tube.
 29. The electrode assembly ofclaim 28, wherein the pin is positioned in an interior of the tube. 30.The electrode assembly of claim 18, wherein the mandrel has a c-shapedcross-section.
 31. The electrode assembly of claim 18, wherein themandrel is fitted around the pin such that first electrode strip and thesecond electrode strip are wound around the pin and the mandrel.
 32. Theelectrode assembly of claim 18, wherein the mandrel is a reinforcingmandrel.
 33. An electrode assembly, comprising: an electricallyconductive, elongate pin; an elongate mandrel mounted on at least aportion of the pin; a first electrode strip in electrical communicationwith the pin and a second electrode strip electrically insulated fromthe pin, a portion of the first electrode strip is positioned betweenthe mandrel and the pin; and the mandrel is fitted around the pin andthe first electrode strip and the second electrode strip are woundaround the pin and the mandrel.
 34. The electrode assembly of claim 33,wherein a portion of the pin extends beyond the spiral roll to form abattery terminal.
 35. The electrode assembly of claim 33, wherein themandrel is crimped onto the pin.
 36. The electrode assembly of claim 33,wherein the mounted mandrel has a channel through which electrolyte canbe injected.
 37. The electrode assembly of claim 33, wherein at leastone separator strip separates the first electrode strip and the secondelectrode strip.
 38. The electrode assembly of claim 33, wherein thefirst electrode strip includes active material positioned on asubstrate, the substrate being positioned between the mandrel and thepin without the active material being positioned between the mandrel andthe pin.
 39. The electrode assembly of claim 33, wherein at least oneweld directly connects the first electrode strip to the pin.
 40. Theelectrode assembly of claim 33, wherein the pin includes an alloy ofPtIr alloy.
 41. The electrode assembly of claim 33, wherein a weldattaches the mandrel to the pin.
 42. The electrode assembly of claim 33,wherein the mandrel includes titanium or an alloy of titanium.
 43. Theelectrode assembly of claim 33, wherein the mandrel includes a tube. 44.The electrode assembly of claim 43, wherein the pin is positioned in aninterior of the tube.
 45. The electrode assembly of claim 33, whereinthe mandrel has a c-shaped cross-section.
 46. The electrode assembly ofclaim 33, wherein the mandrel is a reinforcing mandrel.
 47. An electrodeassembly, comprising: an electrically conductive, elongate pin; anelongate mandrel mounted on at least a portion of the pin, the mandrelhaving a c-shaped cross-section; a first electrode strip in electricalcommunication with the pin and a second electrode strip electricallyinsulated from the pin, the first electrode strip and the secondelectrode strip being wound around the pin; and a first end cap mountedon the pin; the first end cap including an electrical insulator, the pinextending through the electrical insulator, and the pin beinghermetically sealed to the electrical insulator.
 48. The electrodeassembly of claim 47, wherein the mounted mandrel has a channel throughwhich electrolyte can be injected.
 49. The electrode assembly of claim47, wherein at least one separator strip separates the first electrodestrip and the second electrode strip.
 50. The electrode assembly ofclaim 47, wherein the first electrode strip includes active materialpositioned on a substrate, the substrate being positioned between themandrel and the pin without the active material being positioned betweenthe mandrel and the pin.
 51. The electrode assembly of claim 47, whereina weld attaches the mandrel to the pin.
 52. The electrode assembly ofclaim 47, wherein the mandrel includes a tube and the pin is positionedin an interior of the tube.
 53. The electrode assembly of claim 47,wherein the mandrel is fitted around the pin such that the firstelectrode strip and the second electrode strip are wound around the pinand the mandrel.
 54. An electrode assembly, comprising: an electricallyconductive, elongate pin; an elongate mandrel mounted on at least aportion of the pin, the mandrel having a c-shaped cross-section; a firstelectrode strip in electrical communication with the pin and a secondelectrode strip electrically insulated from the pin; and the mandrel isfitted around the pin and the first electrode strip and the secondelectrode strip are wound around the pin and the mandrel.
 55. Theelectrode assembly of claim 54, wherein a portion of the pin extendsbeyond the spiral roll to form a battery terminal.
 56. The electrodeassembly of claim 54, wherein the mounted mandrel has a channel throughwhich electrolyte can be injected.
 57. The electrode assembly of claim54, wherein the first electrode strip includes active materialpositioned on a substrate, the substrate being positioned between themandrel and the pin without the active material being positioned betweenthe mandrel and the pin.
 58. The electrode assembly of claim 54, whereina weld attaches the mandrel to the pin.
 59. The electrode assembly ofclaim 54, wherein the mandrel includes a tube and the pin is positionedin an interior of the tube.